Last week I took some photos of the Andromeda Galaxy, which is visible during the evening hours this month. The photos were taken at the Dunedin Causeway leading out to the Gulf of Mexico, and isn't a very dark area - still within the light pollution red zone using the Dark Site Finder map (see image below). About an hour's worth of exposures were used for the final image - taken with my Nikon D750, Nikkor 300mm f/4 ED PF VR lens, TC-20e III Teleconverter and Sky-Watcher Star Adventurer motorized mount. The mount is probably the most vital step for this type of photography as the Earth is constantly rotating. The mount combats this rotation by moving at the same speed as the sky's apparent movement throughout the night. This is the only way to get a sharp exposure of an object in the sky with an exposure over 1-2 seconds.
In order to get this amount of detail I'm using PixInsight, which is a pretty complicated astrophotography program used for processing images (it's also pretty expensive, so I'm currently using the trial version). If it wasn't for the YouTube tutorials, I would've been completely lost. PixInsight, Photoshop and other programs like it are used by both amateur & professional astronomers to help bring out the details in nebula & galaxy images you've probably seen online.
Just to give you an idea of what each individual exposure looks like, here's a single rejected frame from that evening.
As you can see, there doesn't appear to be much there. No real colors in the image other than the slight red hue from light pollution and over-exposure. What PixInsight does is combine the 60+ images into a stack to maximize the data and photons captured in an hour's time. It also allows me to "stretch" the histogram in order to bring out contrast and colors that are in the image. The program itself is pretty incredible and is used by professional and amateur astrophotographers.
Now I just need to save up the $300+ for the asking price of the software as the trial version will only be good for the next 40 days.